Revert "Fix a build breakage. Looks like the LLVM side of this change has been reverted"

This reverts commit r223375.  We need to use unique_ptr to build with
LLVM r223183.

llvm-svn: 223388

lldb/source/Expression/IRExecutionUnit.cpp

@@ -309,7 +309,7 @@ IRExecutionUnit::GetRunnableInfo(Error &error,
     builder.setEngineKind(llvm::EngineKind::JIT)
     .setErrorStr(&error_string)
     .setRelocationModel(relocModel)
-    .setMCJITMemoryManager(new MemoryManager(*this))
+    .setMCJITMemoryManager(std::unique_ptr<MemoryManager>(new MemoryManager(*this)))
     .setCodeModel(codeModel)
     .setOptLevel(llvm::CodeGenOpt::Less);